Re: Origin of feathers

["John V Jackson" <jjackson@interalpha.co.uk>]

-----Original Message----From: Norton, Patrick Date: 14 April 1998 08:09



>>If the pre-feathers first appear as "peach fuzz" all over the
>animal's body, or at least, in areas well exposed to the air at the
>leading edges (particularly the forelimbs), they will surely increase
>aerial friction and allow a small, wingless, arboreal animal to better
>interact with the air
>when it is in free fall.<
>
>Wouldn't increased *friction* result in increased drag, and therefore
>poorer aerodynamic performance?


To those of us poor benighted fools who see flight as having evolved in
gradual stages, flapping flight was preceded by gliding and steering which
was preceded by parachuting and steering.  "Parachuting" is used in a
relative sense here of course, and simply requires an increase in drag.  It
would have been an essential precursor to the whole sequence, but would
actually have meant just an increase in interaction with the air, which
eventually became more specialised.

Incidentally, the experiment of dropping shaved mice out of the window would
be better done on shaved chickens.  Maybe it's unscientific, but I feel I
already know without having to do it what the result would be if one plucked
chicken were dropped off a skyscraper, and one normal chicken.  Of course it
only matters to animals about the size of a cat, or a chicken . . . or a
large Archaeopteryx.  With animals of a different sort of scale, drag
wouldn't make much difference one way or another.

My imagined scenario was never of peach fuzz but just scales with points (or
plates) on, like pangolins or those small african vipers.  They would
cushion falls better too.

JJ